18 G. LINDSTRÖM, THE ASCOCERATIDAE AND THE LITUITIDA. 
cerus, a name previously employed for a genus of insects. He then also gave the first 
description. He says that the air chambers are not »perpendicular» (h. e. rectangular) to 
the axis of the shell, but nearly parallel and he regarded it as a curved shell in which 
the chambered portion was bent so as partly to embrace the not chambered portion, in 
analogy to Ptychoceras, though both parts of the Ascoceras shell are in close contact. 
Still in 1854 (N. Jahrbuch p. 11) he held this view with the addition that both 
the bent parts were enclosed within the same exterior shell and that the siphuncele stret- 
ched from the body chamber into the air chambers, though it was not yet possible to dis- 
cover how the different chambers were in communication. 
In a new paper (1855 in Bullet. Soc. Géol. XII p. 157, translated in N. Jahrbuch 
p. 257), »Ascoceras as the prototype of Nautilus», he treats of its nature at large. He 
gave up the view of the analogy with Ptychoceras and compares it rather with Endoceras, 
regarding the sigmoid septa along the dorsal side as homologous with those of Endoceras, 
the empty body chamber besides them was then homologous with the large siphuncle of 
that genus and consequently the empty space above it and the air chambers formed the true 
body chamber. He says further that there is no communication between the air chambers 
themselves, nor between them and the body chamber, but there is a small aperture at its 
lower end, which seems to enter into the flattened prolongation of the lowest air chamber, 
Ascoceras was more imperfect than Orthoceras because the shell was more simple. 
At the request of BARRANDE, BRONN sent him some remarks on this paper and these 
remarks, which have not been published, caused BARRANDE to write a sort of postseriptum, 
when the paper was translated in German in the N. Jahrbuch. BRONn accompanied it 
with some very remarkable notes. BARRANDE believed that Ascoceras had beneath the 
sigmoid septa only a single deciduous septum, but BRonn again, what is most important, 
thought that there must have been a series of such, as in Gomphoceras. As for other 
points of resemblance which they and other authors saw between Ascoceras and Gompho- 
ceras see further on. 
Contrary to BARRANDE BRONN also says, that Ascoceras already in an early stage 
of evolution breaks off the part which consists of regular air-chambers. Örthoceras is 
rather to be designated as the early stage of Ascoceras. BARRANDE again contended that 
Ascoceras was the early or lower type, in consequence of the incomplete septa. 
In his last great work, Systeéme Silurien de Bohéme, vol. II part I p. 334, he again 
recapitulates his views concerning the structure and relations of Ascoceras. He maintains 
the perfect analogy with Endoceras and that the lowest part of the body chamber, parallel 
with the air chambers, represents »le large siphon ventral de Endoceras» (p. 347). But be- 
sides this he assumed a smaller siphuncle in the deciduous chambers. He speaks namely 
of two sets of air chambers: one persistent and another of »caduques». The persistent were 
formed of the sigmoid septa and if I catch his meaning rightly, it is evident that he re- 
garded the first sigmoid septum as the first septum of the Ascoceras and which formed 
its bottom, instead of a nearly regular septum, the last of the Nautiloid stage, forming 
the truncated extremity. Hence, when he later on in 1877 (Syst. Sil. vol. II, Supplem. p. 98 
pl. 491) found a specimen with two septa beneath the first sigmoid one, he regarded these 
as deciduous ones, though they in fact are the two first septa of the Ascoceras and the lower- 
